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Hi all,
I just tested the main fuel relay as well as the fuel pump relay by jumping pins 30 and 87 according to the Haynes manual. It noted that there should be a "whirring sound" coming from the trunk area (in tank FP) once the key was turned, but I get no sound at all. I also do not get this sound when the relays are replaced either. Once the car is running at idle it sound s like it is humming, but once I start to drive it loses acceleration completely at intermittent times. Any thoughts?
Thanks,
Lee M
85 528e

Hey man,
Have you checked for power and ground to the intake feed pump yet? If not id start there. Then if you have power and ground feeding the pump but you do not hear the pump running then you know that you have a bad pump. I assume the car is still running at this point correct? The car will run if the main pump is still working even if the in tank pump is not. The symptons of the in tank pump being inop would be running rough when low on fuel or stalling on heavy turns. Give that a try then let us know.
Good Luck

Hey man,
Have you checked for power and ground to the intake feed pump yet? If not id start there. Then if you have power and ground feeding the pump but you do not hear the pump running then you know that you have a bad pump. I assume the car is still running at this point correct? The car will run if the main pump is still working even if the in tank pump is not. The symptons of the in tank pump being inop would be running rough when low on fuel or stalling on heavy turns. Give that a try then let us know.
Good Luck

Hi Dan,
Thanks for responding,
I checked for power to the pumps and both relays and everything checked out as far as that went. According to the Haynes manual that ment the in tank pump was bad so I went and bought one. Big mistake because after I changed it the problem is still there. The difference this time though was I heard a loud knocking from under the trunk while I had it opened, so I'm guessing I changed the wrong pump. Any feedback would be greatly appreciated.
Lee

Hi Dan,
Thanks for responding,
I checked for power to the pumps and both relays and everything checked out as far as that went. According to the Haynes manual that ment the in tank pump was bad so I went and bought one. Big mistake because after I changed it the problem is still there. The difference this time though was I heard a loud knocking from under the trunk while I had it opened, so I'm guessing I changed the wrong pump. Any feedback would be greatly appreciated.
Lee

Hi Lee,
As i said before if the car runs at all then the main pump is working. It may not be putting out sufficient fuel pressure but it is working. My thoughts now are that you definitely need to figure out if that in tank suction pump is working. First of all 1 thing to consider is that just because you have power to the pump does not mean that you have ground. Be sure to check for both. Also remember that by jumping 30 and 87 on the relay that does not mean you are providing power necessarily. The reason I say this is because if a fuse is blown or there is any other problem there may not even be power at 30 on the relay to begin with. Hopefully im making sense. So anyway the thing to do is 1) Make absolute sure that you have power AND ground at the intake fuel pump. 2)Once your sure that you do, then make absolute sure that it is in fact running. (it should be since its new but you never know) NOTE: use a stethescope or a screwdriver with the handle up to your ear to listen to the pump, pull the power connector on and off while the car is running that way you can tell for sure if it comes on when you connect the power. 3) If it is running then you need to check fuel pressure and evaluate if your problem really is in the fuel system or if maybe you are barking up the wrong tree. Let us know how it goes. If it helps you can find me often times at www.bmwtips.com in the e39 chat channel. There we could chat and you could ask me specific questions and get a fast answer. Either way take care and Good Luck,
DanT

Hi Lee,
As i said before if the car runs at all then the main pump is working. It may not be putting out sufficient fuel pressure but it is working. My thoughts now are that you definitely need to figure out if that in tank suction pump is working. First of all 1 thing to consider is that just because you have power to the pump does not mean that you have ground. Be sure to check for both. Also remember that by jumping 30 and 87 on the relay that does not mean you are providing power necessarily. The reason I say this is because if a fuse is blown or there is any other problem there may not even be power at 30 on the relay to begin with. Hopefully im making sense. So anyway the thing to do is 1) Make absolute sure that you have power AND ground at the intake fuel pump. 2)Once your sure that you do, then make absolute sure that it is in fact running. (it should be since its new but you never know) NOTE: use a stethescope or a screwdriver with the handle up to your ear to listen to the pump, pull the power connector on and off while the car is running that way you can tell for sure if it comes on when you connect the power. 3) If it is running then you need to check fuel pressure and evaluate if your problem really is in the fuel system or if maybe you are barking up the wrong tree. Let us know how it goes. If it helps you can find me often times at www.bmwtips.com in the e39 chat channel. There we could chat and you could ask me specific questions and get a fast answer. Either way take care and Good Luck,
DanT

Hi Dan,
I checked the power to the intake fuel pump with the key in the on position and DO NOT HAVE POWER with or without the relay and jumper in place. In fact if I disconnect the pump connection the car runs the same as is does when connected. I do have power to the pump when I start the car though so I left the pump disconnected and now the car seems to run better with the pump disconnected! I don't get it. The hesitation and loss of acceleration are gone but the car does seem to be sluggish from the lack of pressure assistance. Any suggestions?

PS. Around what time are you logged in at that chat room? I live on the East Coast (Jersey) and I heard from justcor your on the West Coast .
Regards,
Lee

Hi Dan,
I checked the power to the intake fuel pump with the key in the on position and DO NOT HAVE POWER with or without the relay and jumper in place. In fact if I disconnect the pump connection the car runs the same as is does when connected. I do have power to the pump when I start the car though so I left the pump disconnected and now the car seems to run better with the pump disconnected! I don't get it. The hesitation and loss of acceleration are gone but the car does seem to be sluggish from the lack of pressure assistance. Any suggestions?

PS. Around what time are you logged in at that chat room? I live on the East Coast (Jersey) and I heard from justcor your on the West Coast .
Regards,
Lee

hi Lee,
Im usually on IRC in the evenings like after 6pm my time. Send me an email and ill try and get you a schematic for the system and tell you where to check for what. As far as suggestions i would suggest you try and fix the known problem first then go from there. If youre not getting power to the in tank fuel pump then thats definitely a problem. I say lets fix that then move on. On an 85 you may have more than 1 thing going on. The key is to systematically eliminate possible causes 1 at a time. E mail me and ill see what i can do to help.
DanTdantech@bmwtips.com